Intralocus sexual conflict can maintain alternative reproductive tactics

Alternative reproductive tactics (ARTs) are ubiquitous throughout the animal kingdom. Multiple mechanisms have been proposed to explain the maintenance of ARTs over time, including disruptive and negative frequency-dependent selection and female choice. However, these mechanisms focus exclusively on selection in the sex exhibiting the polymorphism, potentially limiting our understanding of the evolutionary causes and consequences of ARTs. Here we explore the role that intralocus sexual conflict may play in the maintenance of sex-specific ARTs. We use a genetically explicit individual-based model in which female fecundity and male tactic share a genetic architecture. By modeling ART maintenance under varying selection regimes and levels of sex-specific gene expression, we explore the conditions under which intralocus sexual conflict can maintain a hypothetical ART defined by two color morphs that depend on an underlying liability trait. Our models consistently revealed that sexual conflict can result in the persistence of a sex-specific polymorphism over hundreds of generations, even in the absence of negative frequency-dependent selection. ARTs were maintained through correlated selection when one male ART has lower fitness but produces daughters with higher fitness. Importantly, the maintenance of ARTs through sexual conflict resulted in a significant reduction in population growth rate, indicating that the evolutionary mechanism of ART maintenance can have broad ecological consequences. These results highlight the importance of understanding selection on both sexes when attempting to explain the maintenance of ARTs. Our results are consistent with a growing literature documenting genetic correlations between male ARTs and female fitness, suggesting that the maintenance of sex-specific ARTs through intralocus sexual conflict may be common and widespread in nature.